Question 1

Explain the importance of the Merrifield method in peptide synthesis.

Accepted Answer

In 1969,Bruce Merrifield developed a method that revolutionized the synthesis of peptides by producing them faster and in higher yields.This method became known as automated solid-phase peptide synthesis.The method won him the Nobel Prize in chemistry in 1984.

Question 2

What is the pI of arginine? The structure and pKa values are shown below.

Accepted Answer

A) 10.76 
B) 7)90 
C) 5)61 
D) 7)33 
E) 9)67 
A) 10.76 
B) 7)90 
C) 5)61 
D) 7)33 
E) 9)67 A

Question 3

In nature,which is the most commonly found isomer,L-amino acids or D-amino acids?

Accepted Answer

Unlike monosaccharides where the D-isomers are more common,most amino acids found in nature have the L-configuration.

Question 4

Give a detailed,stepwise mechanism for the formation of the activated acyl derivative from the reaction of an amino acid with N,N'-dicyclohexylcarbodiimide.

Accepted Answer

The answer of Give a detailed,stepwise mechanism for the formation...

Question 5

Name the following compound.

Accepted Answer

A) alanine 
B) leucine 
C) valine 
D) glycine 
E) isoleucine 
A) alanine 
B) leucine 
C) valine 
D) glycine 
E) isoleucine

Question 6

Three dimensional structure of the peptides is also called a

Accepted Answer

A) primary structure. 
B) secondary structure. 
C) tertiary structure. 
D) ternary structure. 
E) quaternary structure. 
A) primary structure. 
B) secondary structure. 
C) tertiary structure. 
D) ternary structure. 
E) quaternary structure.

Question 7

Peptidases cause the

Accepted Answer

A) hydrolysis of peptide bonds. 
B) formation of peptide bonds. 
C) hydrolysis of disulfide bonds. 
D) formation of disulfide bonds. 
E) all of the above. 
A) hydrolysis of peptide bonds. 
B) formation of peptide bonds. 
C) hydrolysis of disulfide bonds. 
D) formation of disulfide bonds. 
E) all of the above.

Question 8

How many amino acids does an oligopeptide contain?

Accepted Answer

A) 2-5 
B) 4-8 
C) 3-9 
D) 4-10 
E) >10 
A) 2-5 
B) 4-8 
C) 3-9 
D) 4-10 
E) >10

Question 9

Draw a line where cleavage occurs with trypsin.

Accepted Answer

The answer of Draw a line where cleavage occurs with...

Question 10

What is the name of the amino acid produced when propanoic acid is subjected to the following sequence of reagents? 1.PBr3,Br2
2)H2O
3)NH3,Δ

Accepted Answer

A) alanine 
B) aspartic acid 
C) glutamic acid 
D) valine 
E) asparagine 
A) alanine 
B) aspartic acid 
C) glutamic acid 
D) valine 
E) asparagine

Question 11

Which of the following amino acids will be closest to the origin when separated by thin-layer chromatography?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 12

Which of the following is the first step in the determination of the primary structure of proteins?

Accepted Answer

A) determining the number and kind of amino acids in the peptide 
B) reducing the disulfide bridges in the protein 
C) protecting the N-terminal of the peptide 
D) protecting the C-terminal of the peptide 
E) hydrolyzing the protein with dilute acid 
A) determining the number and kind of amino acids in the peptide 
B) reducing the disulfide bridges in the protein 
C) protecting the N-terminal of the peptide 
D) protecting the C-terminal of the peptide 
E) hydrolyzing the protein with dilute acid

Question 13

Which of the following is a peptidase?

Accepted Answer

A) trypsin 
B) carboxypeptidase A 
C) chymotrypsin 
D) elastase 
E) all of the above 
A) trypsin 
B) carboxypeptidase A 
C) chymotrypsin 
D) elastase 
E) all of the above

Question 14

Treatment of a decapeptide with Edman's reagent releases PTH-Ala.What conclusion can be drawn regarding the decapeptide's primary structure?

Accepted Answer

The N-terminal resid

Question 15

Complete hydrolysis of a hexapeptide gives 2 Gly,Leu,Phe,Pro,and Tyr.Reaction of the peptide with phenylisothiocyanate gave the phenylthiohydantoin of Pro.Partial hydrolysis of the peptide gave the following fragments: Phe-Gly-Tyr,Gly-Phe-Gly,Pro-Leu-Gly,Leu-Gly-Phe.What is the structure of the peptide?

Accepted Answer

Pro-Leu-Gl

Question 16

When a disulfide linkage is formed,the compound containing this new linkage has been

Accepted Answer

A) hydrolyzed. 
B) dehydrated. 
C) electrolyzed. 
D) oxidized. 
E) reduced. 
A) hydrolyzed. 
B) dehydrated. 
C) electrolyzed. 
D) oxidized. 
E) reduced.

Question 17

Which of the following protein structures does denaturation destroy?

Accepted Answer

A) primary and secondary structures 
B) secondary and tertiary structures 
C) tertiary and quaternary structures 
D) secondary,tertiary,and quaternary structures 
A) primary and secondary structures 
B) secondary and tertiary structures 
C) tertiary and quaternary structures 
D) secondary,tertiary,and quaternary structures

Question 18

Define what is meant by isoelectric point (pI)and give an example.

Accepted Answer

Isoelectric point is the pH of an amino

Question 19

Rate the following amino acids in decreasing order of migration towards the cathode (negative electrode)when separated by electrophoresis in a solution of pH= 7.3.
I.lysine: pI= 9.87
II.alanine: pI= 6.02
III.aspartate: pI= 5.95

Accepted Answer

The answer of Rate the following amino acids in decreasing...

Question 20

Explain what essential amino acids are and list all of them.

Accepted Answer

An essential amino acid is one that huma

Exam 21: Amino Acids,peptides,and Proteins

Explain the importance of the Merrifield method in peptide synthesis.

What is the pI of arginine? The structure and pKa values are shown below.

In nature,which is the most commonly found isomer,L-amino acids or D-amino acids?

Give a detailed,stepwise mechanism for the formation of the activated acyl derivative from the reaction of an amino acid with N,N'-dicyclohexylcarbodiimide.

Name the following compound.

Three dimensional structure of the peptides is also called a

Peptidases cause the

How many amino acids does an oligopeptide contain?

Draw a line where cleavage occurs with trypsin.

What is the name of the amino acid produced when propanoic acid is subjected to the following sequence of reagents? 1.PBr3,Br2 2)H2O 3)NH3,Δ

Which of the following amino acids will be closest to the origin when separated by thin-layer chromatography?

Which of the following is the first step in the determination of the primary structure of proteins?

Which of the following is a peptidase?

Treatment of a decapeptide with Edman's reagent releases PTH-Ala.What conclusion can be drawn regarding the decapeptide's primary structure?

When a disulfide linkage is formed,the compound containing this new linkage has been

Which of the following protein structures does denaturation destroy?

Define what is meant by isoelectric point (pI)and give an example.

Rate the following amino acids in decreasing order of migration towards the cathode (negative electrode)when separated by electrophoresis in a solution of pH= 7.3. I.lysine: pI= 9.87 II.alanine: pI= 6.02 III.aspartate: pI= 5.95

Explain what essential amino acids are and list all of them.

Remembering General Chemistry: Electronic Structure and Bonding

Acids and Bases: Central to Understanding Organic Chemistry

An Introduction to Organic Compounds: Nomenclature, physical Properties, and Structure

Isomers: the Arrangement of Atoms in Space

Alkenes: Structure,nomenclature,and an Introduction to Reactivity - Thermodynamics and Kinetics

The Reactions of Alkenes - the Stereochemistry of Addition Reactions

The Reactions of Alkynes - Introduction to Multistep Synthesis

Delocalized Electrons: Their Effect on Stability, pka, and the Products of a Reaction - Aromaticity and Electronic Effects: an Introduction to the Reactions of Benzene

Substitution and Elimination Reactions of Alkyl Halides

Reactions of Alcohols, ethers, epoxides, amines and Sulfur-Containing Compounds

Organometallic Compounds

Radicals

Mass Spectrometry,infrared Spectroscopy,and Uvvis Spectroscopy

Nmr Spectroscopy

Reactions of Carboxylic Acids and Carboxylic Acid Derivatives

Reactions of Aldehydes and Ketones

Reactions at the Α-Carbon

Reactions of Benzene and Substituted Benzenes

More About Amines - Reactions of Heterocylic Compounds

The Organic Chemistry of Carbohydrates

Catalysis in Organic Reactions and in Enzymatic Reactions

The Organic Chemistry of the Coenzymes, compounds Derived From Vitamins

The Organic Chemistry of the Metabolic Pathways

The Organic Chemistry of Lipids

The Chemistry of the Nucleic Acids

Synthetic Polymers

Pericyclic Reactions

Filters

What is the name of the amino acid produced when propanoic acid is subjected to the following sequence of reagents? 1.PBr₃,Br₂ 2)H₂O 3)NH₃,Δ